4. Patient examination and re-evaluation: Laboratory data of complete blood count (CBC)/differential count (DC), creatinine, alanine aminotransferase (ALT) will be routine checked every weeks during the first 3 treatment cycles. During all treatment courses, if grade 4 neutropenia or grade 4 thrombocytopenia attacked, the laboratory will be checked every 3 days until recovered to pre-treatment baseline. Around 70% responsive and stable cases could be enrolled in the 4th treatment cycle will be routine checked the laboratory data before gemcitabine administration. Plasma EBV DNA copies number will be monitored before each cycle treatment. Systemic re-evaluation will be performed after every three cycles treatment. Re-evaluation including physical examination, image studies including CT/MRI for head and neck area, chest x-ray, abdominal echo, and Gallium whole body tumor scan, and blood exam including complete CBC count, biochemical profile, and plasma EBV DNA copies number.